Nylon compositions for golf ball covers and method of making same

ABSTRACT

Disclosed herein is a golf ball with a cover formed from a polyamide composition and a method of making the same. More specifically, the golf ball has a cover which contains a combination of a polyamide component and an ionomeric component or a non-ionomeric terpolymer component. The cover composition has excellent durability and resistance to cracking, even at cold temperatures. The nylon-ionomer blend is a useful substitute for an ionomer golf ball cover, particularly when a low spin golf ball is desired.

This is a divisional of U.S. application Ser. No. 08/763,070 filed onDec. 10, 1996 which is now U.S. Pat. No. 5,886,103.

FIELD OF THE INVENTION

The present invention relates to compositions suitable for golf ballconstructions, and to golf balls which employ those compositions.

BACKGROUND OF THE INVENTION

Modern golf balls typically employ ionomeric resins as cover materials.lonomeric resins, as a result of their toughness, durability, and widerange of hardness values have become materials of choice for golf ballcovers over traditional rubbers. lonomeric resins generally comprise anα-olefin and an α, β ethylenically unsaturated mono- or dicarboxylicacid neutralized with metal ions to the extent desired. Olefins whichhave been employed to prepare ionomeric resins include ethylene,propylene, butene-i and the like. Unsaturated carboxylic acids whichhave been employed to prepare ionomeric resins include acrylic,methacrylic, ethacrylic, o-chloroacrylic, crotonic, maleic, fumaric,itaconic and the like. lonomeric resins include copolymers of ethylenewith acrylic acid such as those sold by Exxon Corporation under thetrademark “IOTEK”, as well as copolymers of ethylene with methacrylicacid such as those sold by E.I. DuPont Nemours & Company under thetrademark “SURLYN”. In some instances, a softening comonomer such as anacrylate ester has been included such that the ionomeric copolymer is anionomeric terpolymer. Although various compositions have been employedto provide golf balls of varying playability characteristics, a needcontinues for compositions and covers which can be employed to providegolf balls which exhibit good playability and durability.

There are no commercially available golf balls which are generally knownto contain nylon. Nylon alone would be too brittle for use in a golfball cover. When efforts have been made in other fields to blend nylonwith softer materials some degree of incompatibility often has resulted,rendering the blends susceptible to cracking and premature failure. U.S.Pat. No. 4,690,981, the contents of which are incorporated herein byreference, shows soft terpolymer ionomers of ethylene/unsaturatedcarboxylic acid/softening comonomer which are useful in injection-moldeditems such as ski boots, ice skate shells, as coatings for fabrics, andas a replacement for balata in golf balls. The unsaturated carboxylicacid may be, for example, acrylic acid and methacrylic acid. Thesoftening comonomer is, for example, an alkyl acrylate such as n-butylacrylate. The '981 patent briefly mentions that the ionomers can beblended with other materials such as nylon, polypropylene,propylene-ethylene copolymers, linear polyethylene, andethylene/unsaturated carboxylic acid copolymers. However, there is noindication that blends can be used for golf balls.

SUMMARY OF THE INVENTION

An object of the invention is to provide a highly durable golf ball.

Another object of the invention is to provide a golf ball with a coverlayer containing reduced quantities of ionomer.

A further object of the invention is to provide a golf ball having ahigh coefficient of restitution.

Another object of the invention is to provide a durable golf ball with alow spin rate.

Yet another object of the invention is to provide a golf ball having ahard cover layer which is resistant to cracking.

Another object of the invention is to provide a method of making a golfball with a cover layer of the type described above.

Other objects of the invention will be in part obvious and in partpointed out more in detail hereinafter.

The invention in a preferred form is a golf ball having a cover layerwith a resin composition comprising a combination of a polyamidecomponent and an ionomeric component, the content of the polyamidecomponent being at least 23 wt % of the resin composition, the golf ballhaving a coefficient of restitution of at least 0.750. The polyamidecomponent preferably includes at least one member selected from thegroup consisting of a polyamide homopolymer and a polyamide copolymer.In one preferred form of the invention, at least a portion of thepolyamide component and at least a portion of the ionomeric componentare part of the same copolymer. In another form of the invention, thepolyamide component is present in a mixture with the ionomericcomponent. The combination preferably has 23-85 wt % polyamide componentand at least 15-77 wt % ionomeric component.

In one particularly preferred form of the invention, the combinationfurther includes an ester component. The ester component can be, forexample, an olefin ester component. At least a portion of each of thepolyamide component, ionomeric component and ester component preferablyare part of the same copolymer. The composition of this embodimentoptionally further comprises a carboxylic acid-containing copolymerwhich includes at least one member selected from the group consisting ofionomeric copolymers and non-ionomeric terpolymers and which is mixedwith the copolymer of polyamide, ionomer and ester components.

In another particularly preferred form of the invention, the ionomericcomponent includes an acrylate ester. The polyamide component preferablyis in a mixture with the ionomeric component. In yet another embodimentof the invention, the combination of a polyamide component and ionomericcomponent is mixed with a non-polyamide-containing copolymer.

Some examples of the invention include a graft copolymer or blend of apolyamide homopolymer with one or both of an ionomeric terpolymer and anionomeric copolymer with two types of monomers. Preferred polyamides foruse according to the invention are polymers of caprolactam such aspolyepsiloncaprolactam (nylon 6), polyhexamethyleneadipamide (nylon 66),and copolymers of nylon 6 and nylon 66. The ionomeric component of theinvention preferably is a copolymer formed from an α-olefin having 2 to8 carbon atoms and an acid which is selected from the group consistingof α, β-ethylenically unsaturated mono- or dicarboxylic acids and isneutralized with cations which include at least one member selected fromthe group consisting of zinc, lithium, sodium, manganese, calcium,chromium, nickel, aluminum, potassium, barium, tin, copper, andmagnesium ions. Preferred cations are zinc, sodium and lithium, andcombinations thereof. In one preferred embodiment, the copolymer isfurther formed from an unsaturated monomer of the acrylate ester classhaving from 1 to 21 carbon atoms. The golf ball preferably has aDurability Rating of at least 2.

Another preferred form of the invention is a golf ball having a coverlayer with a composition comprising a graft copolymer of (1) at leastone of a polyamide homopolymer and a polyamide copolymer and (2) a firstionomeric copolymer which is formed from an α-olefin and a carboxylicacid. The golf ball has a Durability Rating of at least 2. The coverlayer has a Shore D hardness of at least 30.

Yet another preferred form of the invention is a golf ball having acover layer with a composition comprising a nylon backbone with ionomergrafted thereto, the golf ball having a coefficient of restitution of atleast 0.750.

Another preferred form of the invention is a golf ball having a coverlayer with a composition comprising a combination of a polyamide and anon-ionomeric acid copolymer which is formed from an α-olefin, an ester,and a carboxylic acid. The golf ball preferably has a Durability Ratingof at least 2.

A further preferred form of the invention is a golf ball having a coverlayer comprising at least 10 wt % of a graft copolymer ofpolyepsiloncaprolactam and ionomer, the graft copolymer having a yieldtensile strength of about 54 MPa (ASTM D-638), a flexural modulus ofabout 1585 MPa (ASTM D-790), and a drop weight impact at −40° F. ofabout 200 J (ASTM D-3029). In a particularly preferred form of theinvention, the cover layer comprises at least 80 wt % of the graftcopolymer.

Yet another preferred form of the invention is a method of making a golfball. The method comprises steps of obtaining a golf ball core, andforming a cover layer over the core, the cover layer having a resincomposition comprising a combination of a polyamide component and anionomeric component, the content of the polyamide component being atleast 23 wt % of the resin composition, the golf ball having acoefficient of restitution of at least 0.750.

The invention comprises the several steps in the relation of one or moresuch steps with respect to each of the others, and the articlepossessing the features, properties and the relation of elementsexemplified in the following detailed disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically shows the durability test apparatus used todetermine the durability of the golf balls of the invention.

FIG. 2 is a partial side view of a portion of an insert plate in thedurability test apparatus which has grooves intended to simulate a golfclub face.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to golf balls which employ polyamidecontaining constructions, preferably as inner and/or outer covercompositions of golf balls having a core and one, two, or more coverlayers formed thereon. Some non-limiting examples of compositionsaccording to the invention are as follows:

(1) the reaction product (“RP”) of a 3-part reactive mixture ofpolyamide, ionomeric copolymer, and ester,

(2) RP and at least one non-ionomeric terpolymer,

(3) RP with at least one ionomeric copolymer,

(4) a polyamide homopolymer and/or copolymer combined with at least oneionomeric copolymer, and

(5) a polyamide homopolymer and/or copolymer combined with at least onenon-ionomeric carboxylic acid-containing terpolymer.

The low spin golf balls of the invention preferably have a coefficientof restitution of at least 0.780 and more preferably at least 0.800. TheShore D hardness of a hard nylon-containing cover layer generally is atleast 65 (measured generally in accordance with ASTM D-2240, butmeasured on the curved surface of the ball). The PGA compression of thehard cover layer generally is 85-117, more preferably 90-105, and mostpreferably 90-97. The high spin, softer golf balls of the inventionpreferably have a COR of at least 0.775 and more preferably at least0.790, a Shore D hardness of 30-60, and a PGA compression of 70-100,more preferably 75-95 and most preferably 75-85. Both hard and softnylon-containing covers preferably have a melt index of 0.5-20 g/10min., more preferably 0.5-8 g/10 min., and most preferably 1-4 g/10mins.

An “ionomeric copolymer” as this term is used herein is a copolymer ofan α-olefin and an α, β-ethylenically unsaturated mono- or dicarboxylicacid with at least 3% of the carboxylic acid groups being neutralizedwith metal ions. The α-olefin preferably has 2-8 carbon atoms, thecarboxylic acid preferably is acrylic acid, methacrylic acid, maleicacid, or the like and the metal ions include at least one cationselected from the group consisting of ions of zinc, magnesium, lithium,barium, potassium, calcium, manganese, nickel, chromium, tin, aluminum,sodium, copper, or the like. Preferably the cation is zinc, sodium orlithium or a combination thereof. The term “copolymer” includes (1)copolymers having two types of monomers which are polymerized together,(2) terpolymers (which are formed by the polymerization of three typesof monomers), and (3) copolymers which are formed by the polymerizationof more than three types of monomers.

A “polyamide component” as used herein is a polyamide homopolymer, apolyamide copolymer containing two or more types of amide units, e.g.nylon 6, 12, or a combination of both a polyamide homopolymer and apolyamide copolymer. The polyamide component preferably is a long chainpolymer, not an oligomer, which typically is a short chain polymer of2-10 units. An “ionomeric component” is (a) a non-polyamide-containingionomeric copolymer which is capable of being mixed or blended with thepolyamide component, (b) the ionomeric portion of a polyamide-containingionomeric copolymer, or a combination of both (a) and (b). If thepolyamide component and ionomeric component are bonded to one another,the acid portion of the ionomeric component preferably is neutralizedbefore the reaction of the polyamide and ionomeric components, but mostprobably could also be neutralized after the reaction of the polyamideand ionomeric components.

The details of interaction between a polyamide and an ionomericcopolymer are not fully understood. A polyamide and an ionomer could,for example, be intimately mixed without any bonding but with specificintermolecular interactions. Furthermore, it is possible, in combining aspecific quantity of polyamide with a specific quantity of ionomericcopolymer that portions of the overall quantities of the polyamidecomponent and ionomeric component could be bonded to each other, as in agraft reaction, while other portions of the polyamide component andionomeric component could form a blend which may have specificintermolecular interactions. Thus, this application is not intended tobe limited by the degree of bonding versus intermolecular interaction ofthe polyamide component and ionomeric component unless specificallyindicated.

In a first embodiment, golf balls of the invention employ, preferably asa cover, a composition that is the reaction product (“RP”) of a reactivemixture of polyamide, ionomeric copolymer, and an ester. The RPpreferably is formed from a reactive mixture of at least one ofpolyepsiloncaprolactam (Nylon 6) and polyhexamethyleneadipamide (Nylon66), zinc neutralized ethylene/methacrylic acid ionomer copolymer, andethylene (meth)acrylate. As used herein, the term “(meth)acrylate”includes both acrylates and methacrylates. The polyamide preferably isabout 50 wt % to about 90 wt % of the reactive mixture, the ioniccopolymer is about 5-50 wt % of the reactive mixture, and the copolymeris about 1-20 wt % of the reactive mixture. More preferably, thepolyamide is about 60-72 wt % of the reactive mixture, the ioniccopolymer is about 26-34 wt % of the reactive mixture, and the estercopolymer, preferably olefin ester copolymer, is about 2-6 wt % of thereactive mixture.

Commercially available products which are the reaction products ofreactive mixtures of polyamide, ionic copolymer, and olefin estercopolymer include CAPRON 8351, available from Allied Signal. Thisreactive mixture, and the processing thereof, is believed to bedescribed in U.S. Pat. No. 4,404,325, the teachings of which areincorporated herein by reference in their entirety. As describedtherein, the preferred polyamide is polyepsiloncaprolactam orpolyhexamethyleneadipamide, most preferably polyespiloncaprolactam. Thepreferred olefin ester copolymer is ethylene/ethyl acrylate. Thepreferred ionic copolymer is a Zn neutralized copolymer ofethylene/methacrylic acid available from DuPont under the trade nameSURLYN 9721 (1801). According to claim 7 of U.S. Pat. No. 4,404,325, thepolyamide is present in the reactive mixture in an amount of about 60-72wt %, the ionomeric copolymer is present in an amount of about 26 wt %to about 34 wt %, and the olefin ester copolymer is present in an amountof about 2 to about 6 wt %, based on the total weight of the reactivemixture. It is believed that CAPRON 8351 has a nylon backbone withionomer grafted thereto. Allied Signal states that CAPRON 8351 is agraft copolymer which has the properties shown in Table 1 below.

TABLE 1 Test Method Property (ASTM) Value Specific Gravity D-792 1.07Yield Tensile Strength, psi (MPa) D-638 7800 (54) Ultimate Elongation %D-638 200 Flexural Strength, psi (MPa) D-790 9500 (65) Flexural Modulus,psi (MPa) D-790 230,000 (1585) Notched Izod Impact ft-lbs/in D-256 Nobreak Drop weight Impact ft-lbs (J) D-3029 150 (200) Drop weight Impact@ −40F., ft-lbs (J) D-3029 150 (200) Heat Deflection temp. @ 264 psi, °C. D-648 60 Melting Point, ° C. D-789 215

CAPRON 8351 is the most preferred RP for use in the invention.Variations of CAPRON 8351 also may be used. For example, variations ofCAPRON 8351 which may be used include those which employpolyepsiloncaprolactam or polyhexamethyleneadipamide with olefin estercopolymers such as ethylene/methyl acrylate, ethylene/ethylmethacrylate, and ethylene/methyl methacrylate. Ionic copolymers whichmay be used in variations of CAPRON 8351 include ionic copolymers of analpha olefin of the formula RCH═CH₂ where R is H or alkyl radicalshaving 1-8 carbons, and an α, β ethylenically unsaturated carboxylicacid having from 3-8 carbons. The ionic copolymer has at least about 10wt % of the COOH groups neutralized with metal cations, preferably Zn.Examples of these ionic copolymers include Zn neutralizedethylene/methacrylic acid. In variations of CAPRON 8351, the reactivemixture neutralized to produce such variations may include about 50 wt %to about 90 wt % polyamide, about 5 wt % to 50 wt % ionic copolymer, andabout 1 wt % to 20 wt % olefin ester copolymer, all percents based onthe weight of the reactive mixture.

In another embodiment, golf balls of the invention employ preferably asa cover, a composition that includes RP and at least one terpolymer.Terpolymers which may be employed include olefin/alkyl(meth)acrylate/carboxylic acid terpolymers. These terpolymers typicallyhave about 50-98 wt % olefin, about 1-30 wt % alkyl acrylate, and about1-20 wt % carboxylic acid. The olefin may be any of ethylene, propylene,butene-l, hexene-l and the like, preferably ethylene. The alkyl(meth)acrylate may be any of methyl acrylate, methyl methacrylate, ethylacrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, butylvinyl ether, methyl vinyl ether, and the like, preferably methylacrylate. The carboxylic acid may be any one of acrylic acid,methacrylic acid, maleic acid, and fumaric acid. Monoesters of diacidssuch as methyl hydrogen maleate, methyl hydrogen furmarate, ethylhydrogen fumarate, and maleic anhydride which is considered to be acarboxylic acid may also be used. Preferably, the carboxylic acid isacrylic acid. Useful ethylene/methyl acrylate/acrylic acid terpolymersmay comprise about 98-50 wt %, preferably about 65-85 wt %, mostpreferably about 76 wt % ethylene, about 1-30 wt % preferably 15-20 wt%, most preferably about 18 wt % methyl acrylate, and about 1-20 wt %,preferably about 4-10 wt %, most preferably about 6 wt % acrylic acid.

Olefin/alkyl (meth)acrylate/carboxylic acid terpolymers which arepreferred for use in the compositions employed in the invention areethylene/methyl acrylate/acrylic acid terpolymers such as those marketedby Exxon Chemical Co. under the name ESCOR. Examples of theseterpolymers include ESCOR ATX 320 and ESCOR ATX 325. The properties ofESCOR ATX 320 and ESCOR ATX 325 as provided by Exxon are presented inTable 2.

TABLE 2 ESCOR ESCOR Property/Resin ATX-320 ATX-325 Melt Index¹ 5.0 g/10min 20.0 g/10 min Density¹ 0.950 g/cc 0.950 g/cc Melting Point¹ 69 C. 67C. Crystallization Temperature¹ 51 C. 50 C. Vicat Softening Temperature200 g² 66 C. 60 C. Tensile Strength @ yield³ 12 MPa 7.8 MPa Hardness⁴ 3430 Elongation @ break³ >800% >800% ¹Exxon Method ²ASTM D 1525 ³ASTM 638⁴Shore D

Other olefin/alkyl (meth)acrylate/carboxylic acid terpolymers which maybe employed with RP in the compositions employed in the inventioninclude but are not limited to:

ethylene/n-butyl acrylatelacrylic acid,

ethylene/n-butyl acrylate/methacrylic acid,

ethylene/2-ethoxyethyl acrylate/acrylic acid,

ethylene/2-ethoxyethyl acylate/methacrylic acid,

ethylene/n-pentyl acrylate/acrylic acid,

ethylene/n-pentyl acrylate/methacrylic acid,

ethylene/n-octyl acrylate/acrylic acid,

ethylene/2-ethyhexyl acrylate/acrylic acid,

ethylene/n-propyl acrylate/acrylic acid,

ethylene/n-propyl acrylate/methacrylic acid,

ethylene/n-heptyl acrylate/acrylic acid,

ethylene/2-methoxylethyl acrylate/acrylic acid,

ethylene/3-methoxypropyl acrylate/acrylic acid,

ethylene/3-ethoxypropyl acrylate/acrylic acid, and

ethylene/acrylate/acylic acid.

Compositions which may be employed to provide golf balls according tothis embodiment of the invention include about 1 to about 90 wt %,preferably about 1 to about 30 wt %, most preferably about 15 wt % RPand about 99 wt % to about 10 wt % terpolymer, preferably about 99 wt %to about 70 wt %, most preferably about 85 wt % terpolymer.

In another embodiment, golf balls of the invention employ, preferably asa cover, compositions which include RP and an olefin/alkylacrylate/carboxylic acid terpolymer ionomer. Typically, the carboxylicacid groups of the terpolymer ionomer are partially (i.e., approximately5-80 percent) neutralized by metal ions such as Li, Na, Zn, Mn, Ni, Ba,Sn, Ca, Mg, Cu and the like, preferably Zn, Na or Li or a combinationthereof, most preferably Zn or Li or a combination thereof. Theseterpolymer ionomers usually have a relatively high molecular weight,e.g., a melt index of about 0.1 to 1000 g/10 min., and/or a weightaverage molecular weight of 5000 up to one million. The ethylene/methylacrylate/acrylic acid terpolymer ionomer may comprise about 50-98 wt %,preferably about 76-75 wt %, most preferably about 76 wt % ethylene,about 1-30 wt %, preferably about 15-20 wt %, most preferably about 18wt % methyl acrylate, and about 1-20 wt %, preferably about 4-10 wt %,most preferably about 6 wt % acrylic acid. Useful terpolymer ionomersinclude, for example, ethylene/methyl acrylate/acrylic acid terpolymerionomers sold by Exxon Chemical Co. under the designation “IOTEK”.Preferred terpolymer ionomers for use in the invention include Znneutralized ethylene/methyl acrylate/acrylic acid terpolymer ionomerssuch as IOTEK 7520 and IOTEK 7510, and Li neutralized ionomers such asESCOR ATX-320-Li-80.

ESCOR ATX 320 Li-80 is produced by utilizing a 6.0 wt % acrylicacid/18.0 wt % methyl acrylate/76 wt % ethylene terpolymer produced byExxon Chemical Co. under the designation ESCOR ATX 320. The acid groupspresent in the terpolymer then are neutralized to 80 mol % by Li usinglithium hydroxymonohydrate. Neutralization is performed by addinglithium hydroxymonohydrate and ESCOR ATX 320 terpolymer to an intensivemixer (Banbury® type). The Li salt solubilizes in the ATX 320 terpolymerabove the melting temperature of the terpolymer, and a vigorous reactionoccurs with foaming as the Li cation reacts with the acid groups of theterpolymer, and volatile byproducts are evaporated. The reaction iscontinued until foaming ceases (i.e., about 30-45 minutes at 250-350 F.)and the batch is removed from the Banbury mixer. Mixing continues on ahot two-roll mill (175 F.-250 F.) to complete the neutralizationreaction.

For the purpose of determining the weight percent of neutralization ofthe acrylic acid groups in the terpolymer ionomer after reacting withthe Li salt, it is assumed that one mol of Li neutralizes one mol ofacrylic acid. The calculations of neutralization are based upon anacrylic acid molecular weight of 72 g/mol, giving 0.067 mols of Li per100 grams of the terpolymer.

Although ESCOR ATX 320 terpolymer can be 80 mol % neutralized by Li, itis to be understood that other degrees of neutralization with Li,ranging from about 3 mol % to about 90 mol %, may be employed to provideuseful ionomers. Thus, for example, ATX 320 that is 20 mol % neutralizedby Li, hereinafter referred to as ATX 320-Li-20 may be employed. Inaddition, various cation salts such as salts of Na, K, Mg, Mn, Ca and Nimay be employed in a manner similar to Li salts to provide various otherESCOR ATX 320 type terpolymer ionomers.

Other terpolymer ionomers which may be used in the compositions employedin this embodiment of the invention include ethylene/alkylester/methacrylic acid terpolymer ionomers such as those disclosed inU.S. Pat. No. 4,690,981, the teachings of which are incorporated byreference in its entirety herein, and which are available from DuPontCorp. under the trade name SURLYN. Properties of five SURLYN terpolymerionomers which may be used in the invention are set forth in Table 3.The terpolymer ionomer may be about 1 wt % to about 99 wt %, preferablyabout 50 wt % to about 99 wt %, most preferably about 85 wt %, allamounts based on the total weight of the RP-terpolymer ionomercomposition. RP may be about 1 wt % to about 99 wt %, preferably about 1wt % to about 50 wt %, most preferably about 15 wt %, all amounts basedon the total weight of the composition.

TABLE 3 Resin/ Surlyn Surlyn Surlyn Surlyn Surlyn Surlyn Surlyn SurlynSurlyn Property ASTM 7930 7940 8020¹ 8528 8550 8660 8120¹ 8320¹ 9020¹Cation Li Li Na Na Na Na Na Na Zn Melt Flow Index D-1238 1.8 2.6 1 1.33.9 10 0.9 0.9 1.1 (g/10 min) Density D-792 0.94 0.94 0.95 0.94 0.940.94 0.94 0.94 0.96 Notched Izod D-256 NB¹ NB¹ NB¹ 11.4 — 16 — — NB²Tensile Impact D-1822S 140 220 630 550 795 345 235 213 610 (23 C.)ft-lb/in² Flexural Mod D-790 67 61 14 32 31.7 34 49.1 19.3 14 (23 C.)kpsi Yield Strength D-638 2.8 2.2 — 1.8 1.6 1.9 2.2 2.3 — (kpsi)Elongation (%) D-638 290 285 530 450 419 470 680 770 510 Hardness,D-2240 68 68 56 60 60 62 38 25 55 Shore D Vicat Temp. (C.) D-1525-70 6263 61 73 78 71 51 48 57 Rate B Resin/ Surlyn Surlyn Surlyn Surlyn SurlynSurlyn Surlyn Surlyn Property ASTM 9320¹ 9520 9650 9720 9730 9910 99509970 Cation Zn Zn Zn Zn Zn Zn Zn Zn Melt Flow Index D-1238 0.6 1.1 5 11.6 0.7 5.5 1.4 (g/10 min) Density D-792 0.94 0.95 0.96 0.96 0.95 0.970.96 0.95 Notched Izod D-256 10.1 14.5 NB¹ NB¹ 6.8 NB¹ NB¹ TensileImpact D-1822S 570 460 600 590 485 485 360 (23 C.) ft-lb/in² FlexuralMod D-790 3.7 38 32 36 30 48 37 28 (23 C.) kpsi Yield Strength D-638 3.51.8 1.8 1.7 1.6 2 1.8 1.6 (kpsi) Elongation (%) D-638 500 410 410 440460 290 490 460 Hardness, D-2240 40 60 63 61 63 64 62 62 Shore D VicatTemp. (C.) D-1525-70 454 74 71 71 73 62 66 61 Rate B ¹Terpolymerionomers ²No Break

In another embodiment, golf balls of the invention employ, preferably asa cover, compositions of olefin/carboxylic acid copolymer ionomers madefrom two types of monomers and RP. Olefin/carboxylic acid copolymerionomers which may be employed with RP include those wherein thecarboxylic acid groups of the copolymer ionomer are partially (i.e.,approximately 5-80 percent) neutralized by metal ions such as but notlimited to Li, Na, Zn and Mg, preferably Zn, Na. Ionic copolymers may bezinc neutralized ethylene/methacrylic acid ionomer copolymer, Naneutralized ethylene/acrylic acid copolymer ionomers, and mixturesthereof. The Zn neutralized ethylene/acrylic acid copolymer ionomer canbe the reaction product of Zn neutralization of an ethylene/acrylic acidcopolymer having about 15-20 wt % acrylic acid and a melt index of about37 to about 100. These copolymer ionomers usually have a relatively highmolecular weight, e.g., a melt index of about 0.1 to 1000 g/10 min.,and/or a weight average molecular weight of 5000 up to one million.Useful copolymer ionomers include, for example, ethylene/acrylic acidcopolymer ionomers sold by Exxon Chemical Co. under the designation“IOTEK” such as IOTEK 7030, IOTEK 7020, IOTEK 7010, IOTEK 8030, IOTEK8020, and IOTEK 8000. Non-limiting examples of preferred IOTEK copolymerionomers for use in the invention include IOTEK 7010, IOTEK 7030 andIOTEK 8000. Properties of various IOTEK copolymer ionomers are shown inTables 4-5.

TABLE 4 ASTM IOTEK IOTEK IOTEK IOTEK IOTEK IOTEK IOTEK IOTEK IOTEK*IOTEK* IOTEK Resin/Property Method 4000 4010 7010 7020 7030 8000 80208030 7520 7510 3110 Cation Zn Zn Zn Zn Zn Na Na Na Zn Zn Na Melt FlowIndex g/10 min D-1238 2.5 1.5 0.8 1.5 2.5 0.8 1.6 2.8 2 0.8 1.3 Densitykg/m³ D-792 964 966 968 966 964 957 0.956 956 962 970 939 Melting Point,C. D-2240 85 84 83.5 84 85 83 84 87 67 67 95 Crystallization Point, C.D-638 58 56 55 56 58 45 47 49 39 38 58 Vicat Softening Point, C. D-63860 60 60 60 60 54 54.5 55.5 40 40 75 Flexural Mod, MPa D-790 155 175 190175 155 320 340 355 30 35 260 Tensile Impact at 23 C., D-1822 480 520550 520 480 570 550 500 780 950 580 KJ/m² (Type S Dumbbell, 2 mm ThickCompression Plaques) Plaque Properties (2 mm thick compression molding)Tensile Strength at D-638 22.6 23.5 24.5 23.5 22.6 33 32.5 32 12 15 28Break MPa Yield Point MPa D-638 12 13 14 13 12 19 18.5 18 4 4 14Elongation at Break % D-638 460 450 440 450 460 370 380 410 680 570 5101% Secant Modulus MPa D-638 125 135 150 135 125 280 280 280 22 27 210Shore D Hardness D-2240 52 53 54 53 52 60 60 60 30 35 55 *Terpolymerionomer

TABLE 5 ASTM EX EX EX EX Resin/Property Method 1001 1004 1006 1007Cation EXXON Na Zn Na Zn Melt index (g/10 min) D-1238 1.0 2.0 1.3 1.0Melting Point (C.) D-3417 83.7 82.5 86 85.8 Crystallisation Point (C.)D-3417 41.3 52.5 47.5 52.3 Plaque Properties (2 mm thick compressionmolding) Tensile Strength at Break MPa D-638 34.4 20.6 33.5 24.1 YieldPoint MPa D-638 21.3 14.0 19.3 13.8 Elongation at Break % D-638 341 437421 472 1% Secant Modulus MPa D-638 356 128 314 154 1% Flexural ModulusMPa D-790 365 130 290 152 Shore D Hardness D-2240 63 53 58 51 VicatSoftening Point D-1525 51.5 55 57 60.5

Another embodiment of the invention is golf balls which employ,preferably as a cover, compositions of nylon homopolymer and/orcopolymer and one or more olefin/alkyl acrylate/carboxylic acidterpolymer ionomers. Terpolymer ionomers which may be used with thenylon homopolymers preferably are ethylene/methyl acrylate/acrylic acidterpolymer ionomers. Nylon homopolymers for use in any of thecompositions employed in the invention include but are not limited tonylon 6, nylon 66, and mixtures or copolymers thereof. Other nylons suchas nylon 11, nylon 12, nylon 612, nylon 66/6 and nylon 46 also can beused as long as sufficient durability is achieved. In the case of nylon6, a polyamide chain of about 140-222 repeating units is typicallyuseful, but lower and higher molecular weight material may be employed.CAPRON 8202, a nylon 6 type polymer available from Allied Signal, ispreferred. According to Allied Signal, CAPRON 8202 has the propertiesset forth in Table 6.

TABLE 6 Test Method Property (ASTM) Value Specific Gravity D-792 1.13Yield Tensile Strength, psi (MPa) D-638 11500 (80) Ultimate Elongation %D-638 70 Flexural Strength, psi (MPa) D-790 15700 (110) FlexuralModulus, psi (MPa) D-790 410,000 (2825) Notched Izod Impact, ft-lbs/inD-256 1.0 (55) Heat Deflection Temp., @ 264 psi, ° C. D-648 65 MeltingPoint, ° C. D-789 215 Rockwell Hardness, R Scale D-785 119

Terpolymer ionomers which may be employed include but are not limited tothose having 50-98 wt %, preferably about 76-75 wt %, most preferablyabout 76 wt % ethylene, about 1-30 wt %, preferably about 15-20 wt %,most preferably about 18 wt % methyl acrylate, about 1-20 wt %,preferably about 4-10 wt %, most preferably about 6 wt % acrylic acid,wherein the acrylic acid has been neutralized by Zn, Li or Na orcombinations thereof. Preferred terpolymer ionomers include IOTEK 7520,IOTEK 7510, ESCOR ATX 320-Li-80, or a mixture thereof. The nylonhomopolymer may be present in the compositions an amount of about 1 wt %to about 99 wt %, preferably about 1 wt % to 50 wt %, most preferablyabout 15 wt % of the composition. The terpolymer ionomer may be about 99wt % to about 1 wt %, preferably about 1 wt % to 50 wt %, mostpreferably about 85 wt %, all amounts based on total weight of thecomposition.

ZYTEL 408 is a nylon 66 modified molding compound containing ionomer. Itis believed that ZYTEL 408 is an intimate mixture of polyamide and anionomeric terpolymer of an α-olefin, an acrylate ester, and an α,β-ethylenically unsaturated mono- or dicarboxylic acid with a portion ofthe carboxylic acid groups being neutralized with metal ions. It isunknown to the present inventors whether ZYTEL 408 is a graft copolymeror a blend; however, ZYTEL 408 is believed to be a blend of nylon 66 andan ethylene alkylmethacrylate methacrylic acid terpolymer ionomerneutralized with Zn. The properties of ZYTEL 408, as provided by DuPont,are shown in Table 7.

TABLE 7 Test Method Property (ASTM) Value¹ Specific Gravity D-792 1.09Tensile Strength (−40° F.) D-638 15100 psi Tensile Strength (−40° C.)D-638 104.1 MPa Flexural Modulus (−40° F.) D-790 410,000 psi FlexuralModulus (−40° C.) D-790 2827 MPa Izod Impact Strength at −40° F. D-2561.3 ft. lb./in. Izod Impact Strength at −40° C. D-256 69 J/m GardnerImpact at −30° F. D-3029 >320 ft. lbs. Heat Deflection temp. @ 1.8 · 10⁶Pa D-648 75° C. Melting Point D-789 255° C. ¹Dry as molded, with about0.2% water

A further embodiment of the invention is golf balls which employ,preferably as a cover, compositions of polyamide homopolymers orcopolymers, and olefin/carboxylic acid copolymer ionomers made from twotypes of monomers such as IOTEK. The polyamides which can be used in thecompositions employed in the invention include but are not limited tonylon 6, nylon 66, nylon 11, nylon 12, nylon 612, nylon 66/6, nylon 46and mixtures thereof, as long as sufficient durability is achieved.Preferably, the nylon polymer is any of nylon 6 and nylon 66, mostpreferably nylon 6. In the case of nylon 6, a polyamide chain of about140-222 repeating units is typically useful, but lower and highermolecular weight material may be employed. A preferred polyamidehomopolymer is CAPRON 8202 available from Allied Signal. Usefulcopolymer ionomers include copolymer ionomers having about 99 wt % to 70wt %, preferably about 90 wt % to 80 wt %, most preferably 85 wt %ethylene, about 1 wt % to about 30 wt %, preferably about 10 wt % toabout 20 wt %, most preferably 15 wt % acrylic acid. A preferredethylene/acrylic acid copolymer ionomer is IOTEK 7010 from ExxonChemical Co. The copolymer ionomer may be present in the composition anamount of about 99 wt % to about 1 wt %, preferably about 95 wt % toabout 70 wt %, most preferably about 80 wt % of the composition. Thepolyamide homopolymer may be about 1 wt % to about 99 wt %, preferablyabout 5 wt % to about 30 wt %, most preferably about 20 wt %, whereinall amounts are based on the total weight of the composition.

Two or more copolymer ionomers may be preblended prior to blending withpolyamide homopolymers and/or RP to provide compositions which may beused in the invention. Thus, preblends of hard and soft copolymerionomers, as well as preblends of high carboxylic acid copolymerionomers and low carboxylic acid copolymer ionomers may be utilized toprovide compositions for use in the invention. An Example of such apreblend is a mixture of IOTEK 8000 and IOTEK 7010.

Another embodiment of the invention is golf balls which employ,preferably as a cover, compositions of polyamide homopolymers orcopolymers, and olefin/alkyl acrylate/carboxylic acid terpolymers.Useful terpolymers include terpolymers having about 50-98 wt %,preferably about 76-75 wt %, most preferably about 76 wt % olefin,preferably ethylene, about 1-30 wt %, preferably about 15-20 wt %, mostpreferably about 18 wt % alkyl acrylate, preferably methyl acrylate, andabout 1-20 wt %, preferably about 4-10 wt %, most preferably about 6 wt% carboxylic acid, preferably acrylic acid. The terpolymer may bepresent in the composition an amount of about 1 wt % to about 99 wt %,preferably about 50 wt % to about 99 wt %, most preferably about 85 wt %of the composition. The polyamide homopolymer may be about 1 wt % toabout 99 wt %, preferably about 1 wt % to about 50 wt %, most preferablyabout 15 wt %, wherein all amounts are based on the total weight of thecomposition. Useful polyamides may be of polyepsiloncaprolactam andpolyhexamethyleneadipamide, more preferably nylon 6, nylon 66, nylon 11,nylon 12, nylon 612, nylon 66/6, nylon 46 and mixtures thereof.Preferably, the nylon polymer is any of nylon 6 and nylon 66, still morepreferably nylon 6, most preferably the nylon homopolymer sold by AlliedSignal under the trade name CAPRON 8202. A preferred ethylene/methylacrylate/acrylic acid terpolymer is ESCOR ATX 320 from Exxon ChemicalCo.

Two or more terpolymers may be preblended prior to blending with any ofRP or the polyamide homopolymers to provide compositions which may beused in the invention. Thus, preblends of hard and soft terpolymers, aswell as preblends of high carboxylic acid terpolymers and low carboxylicacid terpolymers may be utilized to provide compositions for use in theinvention.

Although the compositions employed in the invention may be used in golfball construction such as solid cores, one-piece balls and covers, thesecompositions are preferably employed as covers. Golf ball covers can beproduced by injection molding or compression molding the nyloncontaining compositions employed herein over a wound or solid moldedcore, or a liquid core to produce a golf ball having a diameter of about1.680 inches and weighing about 1.620 ounces. The core itself may be ofa uniform composition, or may have two or more layers. The standards forboth the diameter and weight for golf balls are established by theUnited States Golf Association (U.S.G.A.). Although the compositionsemployed in the invention can be used in solid core, two-piece and woundballs, solid and two-piece balls are preferred over wound balls due totheir lower cost and superior performance. The term “solid cores” asused herein refers not only to one piece cores but also to multi-layercores.

Golf balls of the invention may be produced by forming covers whichinclude compositions of the invention around cores by conventionalmolding processes. The cover material is mixed in a rigorous mixingprocedure, preferably using a twin screw extruder or the like and anextrusion temperature of 200-250° C. The cover compositions may beinjection molded directly around the core while the core is positionedin the center of a golf ball mold at temp of about 350 F. to about 450F. In compression molding, the cover composition is first injectionmolded at about 380 F. to about 450 F. to provide smooth surfacedhemispherical shells. The shells are then positioned around the core ina dimpled golf ball mold and compression molded at about 230-300 F. forabout 2 minutes to about 10 minutes at a pressure sufficient to retainthe mold in a closed position. Thereafter, the mold is cooled at about50 F. to about 70 F. for about 2 minutes to about 10 minutes to fuse theshells together to form a unitary ball. After molding, the resultinggolf balls may undergo various further processing steps such as buffing,painting and marking.

The present invention is further illustrated by the followingnon-limiting examples set forth below. In Tables 8-17 which include datafor the examples, the compositions are injection molded at 420-480° F.(depending upon nylon content) around identical solid cores which have afinished diameter of 1.545″ to produce golf balls about 1.680″ indiameter having nominal cover thickness of 0.0675 inches. Each examplerepresents the average data for one dozen balls produced according tothe invention. The properties for the balls listed in the examples aremeasured according to the following procedures:

The resilience or coefficient of restitution (COR) of a golf ball is theconstant “e,” which is the ratio of the relative velocity of an elasticsphere after direct impact to that before impact. As a result, the COR(“e”) can vary from 0 to 1, with 1 being equivalent to a perfectly orcompletely elastic collision and 0 being equivalent to a perfectly orcompletely inelastic collision.

COR, along with additional factors such as club head speed, club headmass, ball weight, ball size and density, spin rate, angle of trajectoryand surface configuration (i.e., dimple pattern and area of dimplecoverage) as well as environmental conditions (e.g. temperature,moisture, atmospheric pressure, wind, etc.) generally determine thedistance a ball will travel when hit. Along this line, the distance agolf ball will travel under controlled environmental conditions is afunction of the speed and mass of the club and size, density andresilience (COR) of the ball and other factors. The initial velocity ofthe club, the mass of the club and the angle of the ball's departure areessentially provided by the golfer upon striking. Since club head, clubhead mass, the angle of trajectory and environmental conditions are notdeterminants controllable by golf ball producers and the ball size andweight are set by the U.S.G.A., these are not factors of concern amonggolf ball manufacturers. The factors or determinants of interest withrespect to improved distance are generally the coefficient ofrestitution (COR) and the surface configuration (dimple pattern, ratioof land area to dimple area, etc.) of the ball.

The COR in solid core balls is a function of the composition of themolded core and of the cover. The molded core and/or cover may becomprised of one or more layers such as in multi-layered balls. In ballscontaining a wound core (i.e., balls comprising a liquid or solidcenter, elastic windings, and a cover), the coefficient of restitutionis a function of not only the composition of the center and cover, butalso the composition and tension of the elastomeric windings. As in thesolid core balls, the center and cover of a wound core ball may alsoconsist of one or more layers.

The coefficient of restitution is the ratio of the outgoing velocity tothe incoming velocity. In the examples of this application, thecoefficient of restitution of a golf ball was measured by propelling aball horizontally at a speed of 125±5 feet per second (fps) andcorrected to 125 fps against a generally vertical, hard, flat steelplate and measuring the ball's incoming and outgoing velocityelectronically. Speeds were measured with a pair of Oehler Mark 55ballistic screens available from Oehler Research, Inc., P.O. Box 9135,Austin, Tex., which provide a timing pulse when an object passes throughthem. The screens were separated by 36″ and are located 25.25″ and61.25″ from the rebound wall. The ball speed was measured by timing thepulses from screen 1 to screen 2 on the way into the rebound wall (asthe average speed of the ball over 36″), and then the exit speed wastimed from screen 2 to screen 1 over the same distance. The rebound wallwas tilted 2 degrees from a vertical plane to allow the ball to reboundslightly downward in order to miss the edge of the cannon that fired it.The rebound wall is solid steel 0.2 inches thick.

As indicated above, the incoming speed should be 125±5 fps but correctedto 125 fps. The correlation between COR and forward or incoming speedhas been studied and a correction has been made over the ±5 fps range sothat the COR is reported as if the ball had an incoming speed of exactly125.0 fps.

The coefficient of restitution must be carefully controlled in allcommercial golf balls if the ball is to be within the specificationsregulated by the United States Golf Association (U.S.G.A.). As mentionedto some degree above, the U.S.G.A. standards indicate that a“regulation” ball cannot have an initial velocity exceeding 255 feet persecond in an atmosphere of 75° F. when tested on a U.S.G.A. machine.Since the coefficient of restitution of a ball is related to the ball'sinitial velocity, it is highly desirable to produce a ball havingsufficiently high coefficient of restitution to closely approach theU.S.G.A. limit on initial velocity, while having an ample degree ofsoftness (i.e., hardness) to produce enhanced playability (i.e., spin,etc.).

Cold cracking resistance is measured by firing a ball, having beenpreviously stored at 10 F. for 24 hours, at a velocity of 165 ft/secfrom an air cannon against a steel plate positioned 12 feet from themuzzle of the cannon. The ball is fired 5 times against the plate. Afterallowing the ball to equilibrate to room temperature, the ball isvisually inspected to identify cracks in the cover. One or more cracks,no matter how small, constitute failure.

The term “compression” utilized in the golf ball trade generally definesthe overall deflection that a golf ball undergoes when subjected to acompressive load. For example, PGA compression indicates the amount ofchange in golf ball's shape upon striking. The development of solid coretechnology in two-piece balls has allowed for much more precise controlof compression in comparison to thread wound three-piece balls. This isbecause in the manufacture of solid core balls, the amount of deflectionor deformation is precisely controlled by the chemical formula used inmaking the cores. This differs from wound three-piece balls whereincompression is controlled in part by the winding process of the elasticthread. Thus, two-piece and multilayer solid core balls exhibit muchmore consistent compression readings than balls having wound cores suchas the thread wound three-piece balls.

In the past, PGA compression related to a scale of from 0 to 200 givento a golf ball. The lower the PGA compression value, the softer the feelof the ball upon striking. In practice, tournament quality balls havecompression ratings around 70-110, preferably around 80 to 100.

In determining PGA compression using the 0-200 scale, a standard forceis applied to the external surface of the ball. A ball which exhibits nodeflection (0.0 inches in deflection) is rated 200 and a ball whichdeflects {fraction (2/10)}th of an inch (0.2 inches) is rated 0. Everychange of 0.001 of an inch in deflection represents a 1 point drop incompression. Consequently, a ball which deflects 0.1 inches (100×0.001inches) has a PGA compression value of 100 (i.e., 200-100) and a ballwhich deflects 0.110 inches (110×0.001 inches) has a PGA compression of90 (i.e., 200-110).

In order to assist in the determination of compression, several deviceshave been employed by the industry. For example, PGA compression isdetermined by an apparatus fashioned in the form of a small press withan upper and lower anvil. The upper anvil is at rest against a 200-pounddie spring, and the lower anvil is movable through 0.300 inches by meansof a crank mechanism. In its open position the gap between the anvils is1.780 inches allowing a clearance of 0.100 inches for insertion of theball. As the lower anvil is raised by the crank, it compresses the ballagainst the upper anvil, such compression occurring during the last0.200 inches of stroke of the lower anvil, the ball then loading theupper anvil which in turn loads the spring. The equilibrium point of theupper anvil is measured by a dial micrometer if the anvil is deflectedby the ball more than 0.100 inches (less deflection is simply regardedas zero compression) and the reading on the micrometer dial is referredto as the compression of the ball. In practice, tournament quality ballshave compression ratings around 80 to 100 which means that the upperanvil was deflected a total of 0.120 to 0.100 inches.

An example to determine PGA compression can be shown by utilizing a golfball compression tester produced by Atti Engineering Corporation ofNewark, N.J. The value obtained by this tester relates to an arbitraryvalue expressed by a number which may range from 0 to 100, although avalue of 200 can be measured as indicated by two revolutions of the dialindicator on the apparatus. The value obtained defines the deflectionthat a golf ball undergoes when subjected to compressive loading. TheAtti test apparatus consists of a lower movable platform and an uppermovable springloaded anvil. The dial indicator is mounted such that itmeasures the upward movement of the springloaded anvil. The golf ball tobe tested is placed in the lower platform, which is then raised a fixeddistance. The upper portion of the golf ball comes in contact with andexerts a pressure on the springloaded anvil. Depending upon the distanceof the golf ball to be compressed, the upper anvil is forced upwardagainst the spring.

Alternative devices have also been employed to determine compression.For example, Applicant also utilizes a modified Riehle CompressionMachine originally produced by Riehle Bros. Testing Machine Company,Phil., Pa. to evaluate compression of the various components (i.e.,cores, mantle cover balls, finished balls, etc.) of the golf balls. TheRiehle compression device determines deformation in thousandths of aninch under a fixed initialized load of 200 pounds. Using such a device,a Riehle compression of 61 corresponds to a deflection under load of0.061 inches.

Additionally, an approximate relationship between Riehle compression andPGA compression exists for balls of the same size. It has beendetermined by Applicant that Riehle compression corresponds to PGAcompression by the general formula PGA compression=160—Riehlecompression. Consequently, 80 Riehle compression corresponds to 80 PGAcompression, 70 Riehle compression corresponds to 90 PGA compression,and 60 Riehle compression corresponds to 100 PGA compression. Forreporting purposes, Applicant's compression values are usually measuredas Riehle compression and converted to PGA compression.

Furthermore, additional compression devices may also be utilized tomonitor golf ball compression so long as the correlation to PGAcompression is know. These devices have been designed, such as a WhitneyTester, to correlate or correspond to PGA compression through a setrelationship or formula.

Durability is determined by firing a golf ball at 135 ft/sec (at 72° F.)into 5-sided steel pentagonal container, the walls of which are steelplates. The container 10, which is shown schematically in FIG. 1, has a19½ inch long insert plate 12 mounted therein, the central portion 14 ofwhich has horizontally extending square grooves on it which are intendedto simulate a square grooved face of a golf club. The grooves, which areshown in an exaggerated form in FIG. 2, have a width 30 of 0.033 inches,a depth 32 of 0.100 inches, and are spaced apart from one another byland areas 34 having a width of 0.130 inches. The five walls 16 of thepentagonal container each have a length of 14½ inches. The inlet wall isvertical and the insert plate is mounted such that it inclines upward60° relative to a horizontal plane away from opening 20 in container 10.The ball travels 15½-15¾ inches horizontally from its point of entryinto the container 10 until it hits the square-grooved central portion14 of insert plate 12. The angle between the line of trajectory of theball and the insert plate 12 is 30°. The balls are subjected to 70 ormore blows (firings) and are inspected at regular intervals for breakage(i.e., any signs of cover cracking or delamination). If a microcrackforms in a ball, its speed will change and the operator is alerted. Theoperator then visually inspects the ball. If the microcrack cannot yetbe observed, the ball is returned to the test until a crack can bevisually detected.

A ball is assigned a Durability Rating according to the following scale.A sample of twelve balls of the same type are obtained and are testedusing the durability test apparatus described in the previous paragraph.If less than all of the balls in the sample survive 70 blows eachwithout cracking, the ball is assigned a Durability Rating of 1. If allof the balls survive 70 blows and one or two of the twelve balls crackbefore 100 blows, the ball is assigned a Durability Rating of 2. If alltwelve balls in the sample survive 100 blows each, but seven or moreballs crack at less than 200 blows each, the ball is assigned aDurability Rating of 3. If all twelve balls in the sample survive 100blows and at least six out of the twelve balls in the sample alsosurvive 200 blows, the ball is assigned a Durability Rating of 4.

The spin rate of the golf ball is measured by striking the ball with a9-iron wherein the club-head speed is about 105 feet per second and theball is launched at an angle of 26 to 34 degrees with an initialvelocity of about 110-115 feet per second. The spin is measured byobserving the rotation of the ball in flight using stop action strobephotography.

“Shore D hardness” of a cover is measured generally in accordance withASTM D-2240, except the measurements are made on the curved surface of amolded cover, rather than on a plaque. Furthermore, the Shore D hardnessof the cover is measured while the cover remains over the core. When ahardness measurement is made on a dimpled cover, Shore D hardness ismeasured at a land area of the dimpled cover.

EXAMPLES 1-28 Use of Nylon-Containing Ionomers in Golf Ball Covers

By blending the ingredients set forth in Tables 8-10 and 13, covercompositions were produced and injection molded around a core to yield atwo piece ball as described above. The balls were then evaluated. Theresults are shown below:

Examples 1-3

Examples 1-3 in Table 8 illustrate golf balls formed from compositionswhich include RP (CAPRON 8351) with ethylene/methyl acrylate/acrylicacid terpolymers (ESCORATX 325), and compositions formed from RP (CAPRON8351) with Zn neutralized ethylene/methyl acrylate/acrylic acidterpolymer ionomers (IOTEK 7520, and IOTEK 7510). The cover material wasblended in a single screw extruder. Cold cracking of Examples 1 and 2may have been a result of molding problems.

TABLE 8 Example/component (grams) 1 2 3 IOTEK 7520 — 1500 — IOTEK 7510 —— 1500 CAPRON 8351 1500 1500 1500 ESCOR ATX 325 1500 — — Cold CrackResistance 2 cracks 2 cracks — at 2 blows at 3 blows 4 cracks at 3cracks at 3 blows 5 blows Durability - 300 hits No Failures No Failures

Examples 4-9

Examples 4-9 in Table 9 show compositions of nylon homopolymers (CAPRON8202) with ethylene/acrylic acid copolymer ionomers (IOTEK 7010 andIOTEK 8000), blends of ethylene/acrylic acid ionomers (IOTEK 7010 andIOTEK 8000), compositions of nylon homopolymers (CAPRON 8202) withterpolymers (ESCOR ATX 320) and terpolymer ionomers such as (ESCORATX-320-Li-80), and of nylon homopolymers (CAPRON 8202) and terpolymers(ESCOR ATX 320) are shown. Blends A, B, C and D were each pre-extrudedin a single screw extruder and were molded over cores having the sameformulation, a Riehle compression in the range of 61-69 and a COR in therange of 0.766-0.778. Example 5 was a control in which no nylon wasused. Examples 4 and 6-9 show that Nylon 6 can be blended with ionomericcopolymers to make a durable golf ball if sufficient mixing occurs. Itwas surprising that the inclusion of 10% nylon (Example 4) produced acover that had nearly the same durability as Control Example 5. InExample 6, a preextrusion of zinc ionomer (IOTEK 7010) with nylon,followed by dry blending with sodium ionomer unexpectedly resulted inbetter durability than the balls of Example 4 although the covers ofExamples 4 and 6 had the same overall composition. While the covers ofExamples 7 and 8 were expected to break as a result of incompatibility,it was instead found that terpolymer and terpolymer ionomer werecompatible with nylon, and no cracking occurred in the 300-blowdurability test.

TABLE 9 Example/ Component (grams) 4 5 (control) 6 7 8 9 Blend A¹ 2000 —— — — — Blend B² — — — — 2000 — Blend C³ — — — 2000 — — Blend D⁴ — — 650— — 1000 IOTEK 8000 — 1500 1350 — — — IOTEK 7010 — 500 — — — —Compression (Reihle) 59 60 59 74 75 60 Coefficient of Restitution 0.8040.805 0.806 0.783 0.767 0.798 Durability⁵ 100 blows 12 12 12 12 12 12200 blows 12 12 12 12 12 12 300 blows 7 8 9 12 12 5 ¹Sample taken frommixture of 2025 g IOTEK 8000, 675 g IOTEK 7010, and 300 g CAPRON 8202.²Sample taken from mixture of 2700 g ESCOR ATX 320 and 300 g CAPRON8202. ³Sample taken from mixture of 1350 g ESCOR ATX 320, 1350 g ESCORATX 320-Li-80, and 300 g CAPRON 8202. ⁴Sample taken from mixture of 1350g IOTEK 7010 and 600 g CAPRON 8202. ⁵Number of balls out of 12 whichsurvived 100 blows, 200 blows and 300 blows

Examples 10-14

Examples 10-14 in Table 10 illustrate compositions which employ one ormore copolymer ionomers (IOTEK, SURLYN) with ZYTEL. These compositionswere prepared and molded into golf balls according to the proceduresabove. The materials were blended using a single screw extruder. Example11 produced the “best” ball of this set of Examples due to its high COR.

TABLE 10 Example/ Component 10 11 12 13 14 IOTEK 4000 35 wt % 42.5 wt %— — — IOTEK 8000 35 wt % 42.5 wt % — — — SURLYN 9910 — — 85 wt % — —SURLYN 9320 — — — 75 wt % 50 wt % ZYTEL 408 30 wt % 15 wt % 15 wt % 25wt % 50 wt % COR 0.784 0.812 0.803 0.784 0.782 Compression 53 54 56 6561 (Reihle) Hardness 70 70 67 50 62 Shore D

Example 15

Example 15 illustrates use of RP in the form of CAPRON 8351 as the coverof a golf ball. The core had a Riehle compression in the range of 85-95and a COR in the range of 0.772-0.789 and was the same type of core aswas used in Examples 16-44. The performance of this ball is shown inTable 13. The resulting ball had low spin and high hardness, which wouldmake it useful for a high handicap player.

Examples 16-20

RP (CAPRON 8351) was admixed with blend BX1 that included a Naneutralized ethylene/acrylic acid copolymer ionomer, a first Znneutralized ethylene/acrylic acid copolymer ionomer, and a componentmixture (masterbatch). The component mixture included a second Znneutralized ethylene/acrylic acid copolymer ionomer. The second Znneutralized ethylene/acrylic acid ionomer was different from the firstZn neutralized ethylene/acrylic acid copolymer ionomer.

More specifically, in examples 16-20, CAPRON 8351 was blended with blendBX1. In blend BX1, the first Na neutralized ethylene/acrylic acidcopolymer ionomer was IOTEK 8000 in an amount of 70 wt % of blend BX1.The first Zn neutralized ethylene/acrylic acid copolymer ionomer wasIOTEK 7010 in an amount of 20 wt % of blend BX1. The component mixtureformed 10wt % of blend BX1. The component mixture contained IOTEK 7030as the second Zn neutralized ethylene/acrylic acid copolymer ionomer inan amount of 75 wt % of the component mixture. The component mixturealso included 24 wt % of UV stabilizer, 0.26 wt % brightener, 0.46 wt %dye and 0.04 wt % antioxidant. Blend BX1 was produced by dry blendingthe Na and Zn copolymer ionomers with the component mixture. Thecomponent mixture employed in the blend BX1 was produced by meltextruding the ingredients of the component mixture at a temperature ofabout 380 F. Mixing of RP and blend BX1 took place using a twin screwextruder designed for intensive mixing. The RP was melt mixed with blendBX1 at a temperature of about 450 F. The resulting compositions thenwere molded into covers and balls as described above. The performance ofballs according to examples 16-20 is shown in Table 13.

Stated more generally, when CAPRON 8351 and blend BX1 are used to form agolf ball cover, CAPRON 8351 is about 1 to 99 wt %, preferably about 20wt % to about 80 wt %, more preferably about 20 wt % of the composition,and blend BX1 is about 1 to 99 wt %, preferably about 20 to about 80 wt% of the composition, more preferably about 80 wt % of the composition.In blend BX1, the first Zn neutralized ethylene/acrylic acid copolymerionomer is about 1 to about 90 wt %, preferably about 20 wt % of blendBX1, the Na neutralized ethylene/acrylic acid copolymer ionomer is about1 to about 90 wt %, preferably about 70 wt % of blend BX1, and thecomponent mixture is about 1 to about 30 wt %, preferably about 10 wt %of blend BX1. Preferably, the second Zn neutralized ethylene/acrylicacid copolymer ionomer in the component mixture is about 75 wt % of thecomponent mixture, with the remainder being additives such asstabilizers for oxidative degradation, stabilizers for thermaldegradation, stabilizers for ultraviolet light degradation, inhibitorsfor oxidative degradation, inhibitors for thermal degradation,inhibitors for ultraviolet light degradation, lubricants, plasticizers,dyes, pigments, fibrous fillers, particulate fillers, and reinforcementnucleating agents. In this embodiment, a wide variety of Na ionomersincluding but not limited to those listed in Table 4, preferably IOTEK8000 may be employed. The first Zn copolymer ionomer may be, forexample, any of those listed in Table 4, preferably IOTEK 7010. Thesecond Zn copolymer ionomer may be, for example, any of those listed inTable 4, preferably IOTEK 7030. The aforesaid component mixturepreferably includes about 75 wt % IOTEK 7030, remainder additives.

As shown by the results in Table 13, the addition of nylon increased thehardness and COR of the balls, increased distance slightly, and reducedspin. It is important to note that the mixture of CAPRON 8351 withionomer resulted in a highly durable product except in Example 17, inwhich the balls broke early. The poor results of Example 17 may havebeen caused by inadequate molding.

Examples 21-24

RP (CAPRON 8351) and blend BX2 that includes a Na neutralizedethylene/acrylic acid copolymer ionomer, a Zn neutralizedethylene/acrylic acid copolymer ionomer, and the above describedcomponent mixture were employed in a golf ball as a golf ball cover.Mixing of RP and blend BX2 took place using a twin screw extruderdesigned for intensive mixing.

In examples 21-24, the first Zn neutralized ethylene/acrylic acidcopolymer ionomer was EX1003 in an amount of 45% of blend BX2, the Naneutralized ethylene/acrylic acid copolymer ionomer was EX1002 in anamount of 45 wt % of blend BX2, and the component mixture was 10 wt % ofblend BX2. The second Zn neutralized ethylene/acrylic acid copolymerionomer in the component mixture was IOTEK 7030 in an amount of 75 wt %of the component mixture. The component mixture also included 24 wt % UVstabilizer, 0.26 wt % brightener, 0.46 wt % dye and 0.04 wt %antioxidant. The performance of balls with these covers is shown inexamples 21-24 of Table 13.

Stated more generally, in this embodiment, CAPRON 8351 is about 1 toabout 99 wt %, preferably about 20-80 wt %, more preferably about 20 wt% of the composition, and blend BX2 is about 1 to about 99 wt %,preferably about 20-80 wt %, more preferably about 80 wt % of thecomposition. In blend BX2, the Na neutralized ethylene/acrylic acidcopolymer ionomer is about 1 to about 90 wt %, preferably about 45 wt %of blend BX2, the Zn neutralized ethylene/acrylic acid copolymer ionomeris about 1 to about 90 wt %, preferably about 45 wt % of blend BX2, andthe component mixture is about 1 to 30 wt %, preferably about 10 wt % ofblend BX2. In this embodiment, the preferred Na neutralized ionomer isEX1002 and the preferred Zn ionomer is EX1003. EX1002 and EX1003 areprovided by Exxon Chemical Co. and the properties of EX1002 and EX1003are shown in Table 11 below.

TABLE 11 ASTM Resin/Property Method EX 1002 EX 1003 Cation Na Zn MeltIndex (g/10 min) D-1235 1.6 1.1 Melting Point (C.) D-3417 83.7 82Crystallization Point (C.) D-3417 43.2 51.5 Plaque Properties (2 mmthick compression molding) Tensile Strength at D-638 31.7 24.8 Break MPaYield Point MPa D-638 22.5 14.9 Elongation at Break % D-638 348 387 1%Secant Modulus MPa D-638 418 145 1% Flexural Modulus MPa D-790 380 147Shore D Hardness D-2240 62 54 Vicat Softening Point D-1525 51.5 56

EX1002 is made by neutralizing an ethylene/acrylic acid copolymer havingabout 18 wt % acrylic acid and a melt index of about 28 with Na toachieve a Na neutralized ethylene/acrylic acid copolymer ionomer thathas a melt index of about 1. EX1003 is made by neutralizing anethylene/acrylic acid copolymer having about 18 wt % acrylic acid havinga melt index of about 28 with Zn to yield a Zn neutralizedethylene/acrylic acid ionomer having a melt index of about 1. Blend BX2is made in the manner employed to make blend BX1. CAPRON 8351 and blendBX2 then are blended together. The resultant compositions then areformed into golf ball covers and golf balls as described above.

As was the case in Examples 16-20, Examples 21-24 also show that theaddition of nylon increases the hardness and COR of the golf balls, andincreases distance slightly while reducing spin.

Examples 25-28

RP (CAPRON 8351) with blend BX3 that included a Na neutralizedethylene/acrylic acid copolymer ionomer, a Zn neutralizedethylene/acrylic acid copolymer ionomer, and the above describedcomponent mixture were employed in a golf ball as a golf ball cover.Mixing of RP with blend BX3 was conducted using a twin screw extruderdesigned for intensive mixing. In examples 25-28, the first neutralizedethylene/acrylic acid copolymer ionomer was EX 990 in an amount of 45 wt% of blend BX3, the Na neutralized ethylene/acrylic acid copolymerionomer was EX 989 in an amount of 45 wt % of blend BX3, and thecomponent mixture was 10 wt % of blend BX3. The second Zn neutralizedethylene/acrylic acid copolymer ionomer in the component mixture wasIOTEK 7030 in an amount of 75 wt % of the component mixture. Thecomponent mixture also included 24 wt % UV stabilizer, 0.26 wt %brightener, 0.46 wt % dye and 0.04 wt % antioxidant. The properties ofEX 989 and EX 990, as provided by Exxon, are shown in Table 12. Theperformance of balls with covers of these compositions is shown inexamples 25-28 of Table 13.

Stated more generally, in this embodiment, CAPRON 8351 is about 1 toabout 99 wt %, preferably about 20-80 wt %, more preferably about 20 wt% of the composition, and blend BX3 is about 1 to about 99 wt %,preferably about 20-80 wt %, more preferably about 80 wt % of thecomposition. In blend BX3, the Na neutralized ethylene/acrylic acidcopolymer ionomer is about 1 to about 90 wt %, preferably about 45 wt %of blend BX3, the first Zn neutralized ethylene/acrylic acid copolymerionomer is about 1 to 90 wt %, preferably about 45 wt % of blend BX3,and the component mixture is about 1 to 30 wt %, preferably about 10 wt% of blend BX3. In this embodiment, the preferred Na ionomer is EX 989.The preferred Zn copolymer ionomer is EX 990. EX 989 is made by*neutralizing an ethylene/acrylic acid copolymer that has about 18 wt %acrylic acid and a melt index of about 100 with Na. EX 990 is made byneutralizing an ethylene/acrylic acid copolymer that has about 18 wt %acrylic acid and a melt index of about 100 with Zn. EX 989 and EX 990are available from Exxon Chemical Co.

As indicated by the results on Table 13, CAPRON 8351 produces a golfball with excellent durability, as well as a very high coefficient ofrestitution and good distance, when used in combination with BX3.

Examples 20, 21 and 25 were controls. In each set of Examples 16-20,21-24 and 25-28, intermolecular interactions are believed to havecaused, or at least contributed to, the reduction in melt index for theblends as compared to the pure materials. Durability of the coverscontaining 20 wt % CAPRON 8351 is better than durability of coverscontaining 40 wt % CAPRON 8351 . However, the 40 wt % CAPRON 8351 coversmet the durability standard for commercial golf balls and resulted in aharder cover.

TABLE 12 Resin/Property EX 989 EX 990 Melt Index (g/10 min) 1.3 1.24Cation type Na Zn Density (kg/m³) 959 977 Vicat Softening Temp. (C.)52/5 55.0 Crystallization Temp. (C.) 40.1 54.4 Melting Point (C.) 92.681.0 Tensile at Yield (MPa) 23.8 16.5 Tensile at Break (MPa) 32.3 23.8Elongation at Break (%) 330 357 1% Secant Modulus (MPa) 389 205 FlexuralModulus (MPa) 340 183 Hardness (Shore D) 62 56 Zwick Rebound (%) 61 48

TABLE 13 % % % % MOLD 100¹⁰ 200¹¹ 300¹² EX BX3 BX2 BX1 C8351 TEMP¹ MI²SIZE³ WT⁴ COMP⁵ COR⁶ HARD⁷ SPIN⁸ DIST DUR⁹ blows blows blows 15 0 100465 5.51 1.679 45.92 56 808 77 5514 251.3** 258 12 10 9 16 20 80 4653.13 1.677 45.57 60 801 75 5984 248.1** 155 9 2 0 17 40 60 460 0.43 1.6845.52 65 B¹³ 73 6891 235.0** —¹³ — — — 18 60 40 450 0.9 1.68 45.41 71803 72 — 248.8** 197 12 6 0 19 80 20 430 3.23 1.68 45.27 73 806 69 7777249.6** 278 12 12 4 20 100 0 430 9.49 1.68 45.13 75 807 67 8375 248.1**335 12 12 8 21 100 0 430 17.5 1.679 45.22 68 821 72 7028 264.7* 171 12 00 22 80 20 430 7.5 1.68 45.3 66 818 73 6988 263.8* 239 12 5 5 23 60 40450 1.45 1.681 45.6 65 815 74 6434 262.8* 139 9 1 0 24 40 60 460 0.621.678 45.56 61 781 75 6300 264.2* —¹³ — — — 25 100 0 430 15.8 1.68 45.2668 819 72 6707 266.0* 157 12 1 0 26 80 20 430 8.08 1.68 45.32 67 819 736842 265.0* 253 12 7 4 27 60 40 430 2.8 1.679 45.38 66 816 75 6257266.1* 172 11 2 0 28 40 60 460 1.39 1.681 45.73 62 813 77 6013 261.7* 551 0 0 ¹Degrees F. ²Melt Index--g/10 min ³Diameter in inches ⁴Weight ingrams ⁵Riehle Compression ⁶Coefficient of Restitution ⁷Hardness--Shore D⁸revs. per min. ⁹Durability--Average No. of hits to failure ¹⁰Number ofballs out of 12 which survived 100 blows ¹¹Number of balls out of 12which survived 200 blows ¹²Number of balls out of 12 which survived 300blows ¹³Broke *Yards total distance after impact with Top Flight Tourmetal wood having 10.5 Deg. loft at 157.96 ft/sec onto firm turf **Yardstotal distance after impact with Top Flight Tour metal wood having 12Deg. loft at 163.3 ft/sec onto soft turf

Examples 29-44 Use of Blends of Copolymer Ionomer and Nylon in Golf BallCovers Examples 29-34

CAPRON 8202 with the aforementioned blend BX1 was employed as a cover ina golf ball. The CAPRON 8202 and blend BX1 were mixed using a twin screwextruder designed for intensive mixing.

In examples 29-34, the Na neutralized ethylene/acrylic acid copolymerionomer was IOTEK 8000 in an amount of 70 wt % of blend BX1, the firstZn neutralized ethylene/acrylic acid copolymer ionomer was IOTEK 7010 inan amount of 20 wt % of blend BX1, and the component mixture is 10 wt %of blend BX1. The second Zn neutralized ethylene/acrylic acid copolymerionomer in the component mixture was IOTEK 7030 in an amount of 75 wt %of the component mixture. The component mixture also included 24 wt % ofUV stabilizer, 0.26 wt % brightener, 0.46 wt % dye and 0.04 wt %antioxidant. The performance of balls which employ those covers is shownas examples 29-34 in Table 14 below.

Stated more generally, in this embodiment, CAPRON 8202 is about 1 toabout 50 wt %, preferably about 20-50 wt %, more preferably about 20 wt% of the composition, and blend BX1 is about 50 to 99 wt %, preferablyabout 50-80 wt %, more preferably about 80 wt % of the composition aslong as a Durability Rating of at least 2 is obtained. The compositionsare formed into golf ball covers and golf balls as described above.

TABLE 14 % % % % MOLD 100¹⁰ 200¹¹ 300¹² EX BX3 BX2 BX1 C8202 TEMP¹ MI²SIZE³ WT⁴ COMP⁵ COR⁶ HARD⁷ SPIN⁸ DIST DUR⁹ blows blows blows 29 0 100465 14.38 1.68 46.3 43 B¹³ 80 7412 — —¹³ — — — 30 20 80 465 15.9 1.6846.02 50 B¹³ 78 — — —¹³ — — — 31 40 60 460 5.32 1.68 45.76 57 B¹³ 75 — ——¹³ — — — 32 60 40 450 1.73 1.68 45.54 67 808 72 7056 251.6** 69 1 0 033 80 20 430 5.68 1.68 45.4 71 809 70 7845 250.9** 178 12 2 0 34 100 0430 9.49 1.68 45.13 75 807 67 8375 248.1** 335 12 12 8 35 100 0 430 17.51.68 45.22 68 821 72 7028 264.7*  171 12 0 0 36 80 20 430 6.23 1.6845.44 66 821 73 6375 265.5*  103 11 0 0 37 60 40 450 2.21 1.68 45.33 63821 75 5826 265.8*  93 9 0 0 38 40 60 460 7.49 1.68 45.96 54 B¹³ 80 4708— —¹³ — — — 39 0 100 465 14.38 1.68 46.3 43 B¹³ 80 7412 — —¹³ — — — 40100 0 430 15.8 1.68 45.26 68 819 72 6707 266*   157 12 1 0 41 80 20 4306.88 1.79 45.39 66 821 74 6607 266.5*  186 12 3 1 42 60 40 450 3.86 1.6845.67 62 824 77 5656 267.1** 150 12 1 0 43 40 60 460 7.49 1.683 45.92 53B¹³ 80 B¹³ — —¹³ — — — 44 0 100 465 14.38 1.68 46.3 43 B¹³ 80 7412 —¹³ —— — ¹Degrees F. ²Melt Index--g/10 min ³Diameter in inches ⁴Weight ingrams ⁵Riehle Compression ⁶Coefficient of Restitution ⁷Hardness--Shore D⁸RPM ⁹Durability--Average No. of hits to failure ¹⁰Number of balls outof 12 which survived 100 blows ¹¹Number of balls out of 12 whichsurvived 200 blows ¹²Number of balls out of 12 which survived 300 blows¹³Broke *Yards total distance after impact with Top Flight Tour metalwood having 10.5 Deg. loft at 157.96 ft/sec onto firm turf **Yards totaldistance after impact with Top Flight Tour metal wood having 12 Deg.loft at 163.3 ft/sec onto soft turf

Examples 35-39

CAPRON 8202 with the aforementioned blend BX2 was employed as a cover ina golf ball. The CAPRON 8202 and blend BX2 were mixed using a twin screwextruder designed for intensive mixing.

In Examples 35-39, the Na neutralized ethylene/acrylic acid copolymerionomer was EX 1002 in an amount of 45 wt % of blend BX2, the first Znneutralized ethylene/acrylic acid copolymer ionomer was EX 1003 in anamount of 45 wt % of blend BX2, and the component mixture was 10 wt % ofblend BX2. The second Zn neutralized ethylene/acrylic acid copolymerionomer in the component mixture was IOTEK 7030 in an amount of 75 wt %of the component mixture. The component mixture also included 24 wt % UVstabilizer, 0.26 wt % brightener, 0.46 wt % dye and 0.04 wt %antioxidant. The performance of balls with those covers is shown inExamples 35-39 of Table 14 above.

Stated more generally, in this embodiment, CAPRON 8202 is about 1 toabout 50 wt %, preferably about 20-50 wt %, more preferably about 20 wt% of the composition, and blend BX2 is about 50 to about 99 wt %,preferably about 50-80 wt %, more preferably about 80 wt % of thecomposition as long as a minimal Durability Rating of 2 is obtained. Thecompositions are formed into golf ball covers and golf balls asdescribed above.

Examples 40-44

CAPRON 8202 with blend BX3 was employed as a golf ball cover of a golfball. The CAPRON 8202 and blend BX3 were mixed using a twin screwextruder designed for intensive mixing. In Examples 40-44, the first Znneutralized ethylene/acrylic acid copolymer ionomer was EX 990 in anamount of 45 wt % of blend BX3, the Na neutralized ethylene/acrylic acidcopolymer ionomer was EX 989 in an amount of 45 wt % of blend BX3, andthe component mixture was 10 wt % of blend BX3. The second Znneutralized ethylene/acrylic acid copolymer ionomer in the componentmixture was IOTEK 7030 in an amount of 75 wt % of the component mixture.The component mixture also included 24 wt % UV stabilizer, 0.26 wt %brightener, 0.46 wt % dye and 0.04 wt % antioxidant. The performance ofballs with those covers is shown in Examples 40-44 of Table 14 above.

Stated more generally, in this embodiment, CAPRON 8202 is about 1 toabout 50 wt. %, preferably about 20-50 wt. %, more preferably about 20wt. % of the composition, and blend BX3 is about 50 to about 99 wt. %,preferably about 50-80 wt. %, more preferably 80 wt. % of thecomposition as long as a minimal Durability Rating of 2 is obtained. Thecompositions are formed into golf ball covers and golf balls asdescribed above.

Examples 45-59 Use of Blends of Terpolymer Ionomer and Nylon in GolfBall Covers

CAPRON 8351 was blended in different amounts with four differentionomeric or non-ionomeric terpolymers, namely SURLYN 9320, IOTEK 7520,ATX 320-Li-40 and DS3076 (Chevron Chemical Co.). DS3076 is an extrusiongrade sodium ionomer resin with a melt index of 0.5 g/10 min (ASTMD-1238) and a flexural modulus of 34,400 psi (ASTM D-790-66). Blendingtook place in a twin screw extruder designed for intensive mixing. Theweight percentages of CAPRON 8351 and the terpolymer materials are shownon Table 15 below. The blend was employed as a cover of a golf ball. Thecovers were placed over cores having the same formulation, Riehlecompression in the range of 82-92, and COR in the range of 0.785-0.805.The physical properties and performance of the resulting balls is shownon Table 15. The inclusion of nylon increased cover hardness and reducedball spin.

On Table 15, scuff resistance measurements were determined as follows:

A Top-Flite tour pitching wedge (1994) with box grooves was obtained andwas mounted in a Miyamae driving machine. The club face was oriented fora square hit. The forward/backward tee position was adjusted so that thetee was four inches behind the point in the downswing where the club wasvertical. The height of the tee and the toe-heel position of the clubrelative to the tee were adjusted in order that the center of the impactmark was about ¾ of an inch above the sole and was centered toe to heelacross the face. The machine was operated at a club head speed of 125feet per second. A minimum of three samples of each ball were tested.Each ball was hit three times.

After testing, the balls were rated according to the following table:

Rating Type of damage 1 Little or no damage (groove markings or dents) 2Small cuts and/or ripples in cover 3 Moderate amount of material liftedfrom ball surface but still attached to ball 4 Material removed orbarely attached

The balls that were tested were primed and top coated.

The addition of nylon caused a slight reduction in scuff resistance inExamples 45-48 and 49-52. However, Examples 45 and 49-51 were found tohave a scuff resistance that was better than a number of commerciallyavailable “soft” golf balls, which typically have a scuff resistance ofabout 1.0. The “best balls” in this set of Examples were those ofExamples 50-51 because they had a soft feel (i.e. low Shore D andrelatively high spin) in conjunction with good scuff resistance.

TABLE 15 % % % % % MOLD EX 9320 7520 ATX DS3076 C8351 TEMP MI SIZE WT 45100 0 3.7 1.6790 45.35 46 90 10 2.3 1.6790 45.55 47 80 20 1.4 1.68045.58 48 70 30 0.6 1.6790 45.68 49 100 0 6.7 1.680 45.52 50 90 10 5.11.681 45.63 51 80 20 3.6 1.681 45.67 52 70 30 2.6 1.681 45.77 53 100 03.1 1.679 45.37 54 90 10 1.5 1.679 45.44 55 80 20 1.2 1.680 45.60 56 7030 0.8 1.680 45.65 57 100 0 58 90 10 59 80 20 DIST DIST EX COMP CORHARD¹ SPIN D² I³ CC⁴ SCUFF⁵ DUR⁶ 45 80 781 71 10550 248 173 NF 0.5 NF 4681 781 74 10299 247 175 NF 1.5 NF 47 79 782 75 10086 248 175 NF 3.0 NF48 78 782 80 9549 248 177 NF 2.0 NF 49 80 781 69 10622 242 172 NF 0.5 NF50 80 781 70 10578 247 173 NF 1.0 NF 51 80 779 74 10468 248 174 NF 1.0NF 52 78 780 80 10245 248 175 1e3⁷ 1.5 NF 53 80 782 74 10405 245 1761e3⁷ 1.5 NF 54 79 783 76 10318 247 177 NF 3.0 NF 55 79 783 80 10147 250176 NF 4.0 NF 56 78 783 84 9559 249 178 NF 4.5 NF 57 58 59 ¹Shore Chardness ²yards, with driver ³yards, with 9-iron ⁴cold crack ⁵scuffresistance ⁶NF = 12/12 balls survived 20 blows in COR machine at 150-160ft/sec. ⁷one break at third blow (most possibly due to molding)

Examples 45, 49, 53 and 57 were controls. As indicated by the results onTable 15, the golf balls of Examples 46-48, 50-51 and 54-56 possessedgood cold crack resistance. Example 52 was believed to fail because ofpoor/inadequate molding. The formations of Examples 57-59 could not bemolded due to difficulties during the extrusion process.

Examples 60-68 Use of Blends of Lithium Ionomer and Nylon in Golf BallCovers

CAPRON 8202 and CAPRON 8351 were blended with various ionomers. In someof the Examples, all of the CAPRON and ionomers were pre-dried andco-extruded. In other Examples, the CAPRON was predried and preextrudedwith one ionomer and subsequently dry blended with another ionomer. Asingle screw extruder was used. The results are shown on Table 16.

As indicated by the results on Table 16, blends of nylon with lithiumionomers resulted in good durability. Example 63 shows a golf ball withparticularly high durability. Core type A had a Riehle compression inthe range of 68-76 and a COR in the range of 0.795-0.805. Core type Bhad a Riehle compression in the range of 54-62 and a COR in the range of0.789-0.797.

TABLE 16 Pre-dried and Co-extruded Dry Blended % % % % % % % % CORE 100¹200² 300³ EX 996 Li 996 Na 7010 BX1 8351 8202 7010 996 Li COMP COR TYPEblows blows blows DUR⁴ 60 50 33.3 16.7 59 826 A 12 7 3 257 61 50 16.733.3 58 826 A 12 10 3 273 62 33.3 16.7 50 59 826 A 12 11 5 261 63 5033.3 16.7 59 824 A 12 12 8 >300 64 100 60 822 A 12 12 11 >300 65 50 33.316.7 49 810 B 12 11 10 >300 66 100 50 806 B 12 12 11 >300 67 50 16.733.3 57 825 A 12 8 6 258 68 50 33.3 16.7 59 824 A 12 11 3 245 ¹Number ofballs out of 12 which survived 100 blows ²Number of balls out of 12which survived 200 blows ³Number of balls out of 12 which survived 300blows ⁴Durability - average number of hits to failure

Examples 69-96 Use of Small Quantities of Nylon in Ionomeric Golf BallCovers

A number of blends were made using up to 30 wt % CAPRON 8351 or 10 wt %CAPRON 8202. The cores were of the same formulation as those of Examples15-28. A twin screw extruder was used for blending. The results areshown on Table 17.

As shown on Table 17, all of the samples exhibited good durability andhad good COR.

TABLE 17 part 1 Ex. # % Ionomer % 8351 % 8202 COMP COR Shore D ColdCrack 100¹ blows 200² blows 300³ blows MI Ionomer Resin is a dryblend of8000/7010 75/25 69 100 0 68 800 70 nb 12 12 7 5.3 70 90 10 66 801 71 nb12 12 4 3.1 71 80 20 66 801 72 nb 12 12 1 2.4 72 70 30 65 800 72 nb 12 80 1.5 73 90 10 65 802 73 nb 12 12 2 3.1 Ionomer resin is a dryblend of8000/7010 50/50 74 100 0 66 803 71 nb 12 12 4 6.2 75 90 10 65 803 72 nb12 12 11 5 76 80 20 64 803 74 nb 12 12 2 3.9 77 70 30 65 801 74 nb 12 121 2.1 78 90 10 66 803 73 nb 12 11 4 5.1 Ionomer resin is a dryblend of1006/1007 50/50 79 100 0 68 802 71 nb 12 12 4 6.7 80 90 10 67 800 71 nb12 12 3 5.2 81 80 20 66 801 73 nb 12 12 4 3.5 82 70 30 65 798 74 nb 1211 1 2 83 90 10 67 802 75 nb 12 12 7 5.2 Ionomer Resin is a dryblend of1002/1003 50/50 Ex. # % Ionomer % 8351 % 8202 Reihle COR Shore D ColdCrack 100¹ blows 200² blows 300³ blows MI 84 100 0 65 805 71 nb 12 12 211.2 85 90 10 65 805 72 nb 12 11 3 7.4 86 80 20 64 804 73 nb 12 10 0 4.687 70 30 67 810 75 1 @ 5th blow 12 4 0 2.8 88 90 10 66 815 75 nb 12 12 05 Ex. # % Ionomer % 8351 Reihle COR Shore D Cold Crack 100¹ blows 200²blows 300³ blows MI Ionomer resin is a dryblend of AD8195/AD8444 50/5089 100 0 66 818 72 nb 12 12 0 13.8 90 90 10 65 816 73 nb 12 12 1 10 9180 20 65 815 74 nb 12 9 1 7.2 92 70 30 64 813 75 nb 12 11 0 8.1 Ionomerresin is a dryblend of AD8195/AD8181 50/50 93 100 0 66 815 73 nb 12 12 06.3 94 490 10 67 817 74 nb 12 9 0 4.3 95 80 20 66 814 74 nb 12 7 0 4.396 70 30 64 812 75 nb 12 4 0 2.3 IOTEK 8000 15% AA Na Precursor 37 MIIOTEK 7010 15% AA Zn Precursor 37 MI IOTEK 1006 15% AA Na Precursor 20MI IOTEK 1007 15% AA Zn Precursor 20 MI IOTEK 1002 18% AA Na Precursor28 MI IOTEK 1003 18% AA Zn Precursor 28 MI AD 8195 Zn AD 8444 Na AD 8181Li ¹Number of balls out of 12 which survived 100 blows ²Number of ballsout of 12 which survived 200 blows ³Number of balls out of 12 whichsurvived 300 blows

Examples 97-143 Tensile Data for Ionomers and Nylon-Ionomer Blends

Tensile data was collected for a number of blends of ionomer and nylon.The results are shown on Table 18. The addition of nylon generallyincreased tensile modulus and energy to break.

TABLE 18 Tensile Data Nylon Break Stress % Strain @ Energy to BreakYield Stress % Strain @ Modulus¹ Ex. Ionomer Type % Nylon PSI BreakIn-Lb PSI Yield PSI 97 8000/7010 (75/25) — 0 3666 211.3 58.8 3203 20.726825 98 8351 10 3834 224.3 65.9 3314 21.4 27723 99 8351 20 3985 217.867 3483 22.1 28777 100 ″ 8351 30 4158 220 70.8 3659 24.9 30363 101 ″8202 10 3751 211.8 62 3412 21.6 27254 102 8000/7010 (50/50) — 0 3496232.5 62 3151 20.1 25930 103 ″ 8351 10 3635 241.6 67.3 3196 20.1 26196104 ″ 8351 20 3869 265.1 76 3193 20.2 26920 105 ″ 8351 30 4075 257.577.8 3355 21.8 26928 106 ″ 8202 10 3684 248.2 69.1 3179 20.9 25584 1071006/1007 (50/50) — 0 3551 239.6 66.1 3162 19.9 26335 108 ″ 8351 10 3677252.8 71.4 3125 20.4 26070 109 ″ 8351 20 3995 254.5 76.2 3320 20.7 27938110 ″ 8351 30 4056 246.1 75.7 3389 22 29071 111 ″ 8202 10 3556 234.865.7 3207 19.8 27561 112 1002/1003 (50/50) — 0 3759 251.8 72.5 3586 18.130593 113 ″ 8351 10 4007 276.4 81.5 3530 18.4 30491 114 ″ 8351 20 4107277.4 84 3551 18.8 30589 115 ″ 8351 30 4305 277.3 87.7 3683 18.1 30671part 2 Break Stress % Strain @ Energy to Break Yield Stress % Strain @Modulus¹ Ex. # Ionomer Nylon % Nylon PSI Break In-Lb PSI Yield PSI 1161002/1003 (50/50) 8202 10 4481 317.2 99.8 3675 17.8 32585 117 — 8351 1008927 478.8 255.1 5085 25.8 56670 118 8351 100 8312 500.4 247.2 4785 27.542281 119 BX1 8351 40 5323 293 106.2 3606 20.6 30198 120 BX1 8351 204584 265 81.8 3293 19.5 28032 121 BX1 0 3907 216.9 62.8 3305 21.6 26094122 8202 100 8434 422.4 248 7064 19.8 63744 123 BX1 8202 80 9223 518.9288.8 5973 17.8 58195 124 BX1 8202 60 7920 484 238.3 5510 18.9 58424 125BX1 8202 40 6072 397.6 158.5 4771 18.1 45577 126 BX1 8202 20 4538 281.496.4 4090 20.7 35404 127 BX1 0 3907 216.9 62.8 3305 21.6 26094 128 BX2 03489 217.2 61.8 3603 19.2 29755 129 BX2 8351 20 3732 245.8 71.3 354019.5 29814 130 BX2 8351 40 5465 352.6 125.2 3834 20.7 32862 131 BX2 835160 7449 459.7 212 4408 34.4 37181 132 BX2 0 3489 217.2 61.8 3603 19.229755 133 BX2 8202 20 4760 314.6 111.7 4462 18.3 37510 134 BX2 8202 406484 422.4 174.4 4971 18.4 44209 Nylon Break Stress % Strain @ Energy toBreak Yield Stress % Strain @ Modulus¹ Ex. # Ionomer Type % Nylon PSIBreak In-Lb PSI Yield PSI 135 BX2 8202 60 7202 456.6 214.4 5288 21.349705 136 BX3 0 3647 184.2 55.3 3866 19.5 31580 137 BX3 8351 20 4010231.7 72.2 3864 19.6 32011 138 BX3 8351 40 5342 327.2 118.2 4058 22.532499 139 BX3 8351 60 7266 454.5 211.2 4695 27.8 43427 140 BX3 0 3647184.2 55.3 3866 19.5 31580 141 BX3 8202 20 4820 323.8 105.5 3768 18.232422 142 BX3 8202 40 6341 448.2 177.2 4236 17.4 40094 143 BX3 8202 607910 488.9 232.7 5154 20.1 50535 ¹tensile modulus

In any of the compositions employed in the invention, additionalmaterials may be added to these compositions employed to provide desiredproperties. These materials include, for example, dyes such asUltramarine sold by Witaker, Clark and Daniels of South Plainfield,N.J., titanium dioxide, UV absorbers and stabilizers. The compositionsalso may include softening agents such as plasticizers and reinforcingmaterials such as glass fibers and inorganic fillers. Antioxidants alsomay be included in the compositions of the invention, conventionally inamounts of about 1% by weight. Useful antioxidants include 4,4′-di(1,1,3,3-tetramethylbutyl) diphenylamine sold under the tradedesignation “Octamine Antioxidant” by Naugatuck Division of US Rubber.Also useful is the hydroperoxide decomposer antidegradant tetrakis(2,4-ditertbutylphenyl)-4,4′-biphenylenediphosphonite sold under thetrade designation “Sandostab P-EPQ” by Sandoz Colors & Chemicals Co.

The compositions employed in the invention may be prepared by anyconventional procedure that provides a substantially uniform admixtureof the components. Preferably drying and melt blending procedures andequipment are used. For example, in preparation of compositions whichemploy nylon materials such as RP with one or more terpolymers and/orterpolymer ionomers, the terpolymer and/or terpolymer ionomer can be drymixed with RP, typically at room temperature, and the resulting mixturemelt blended in any conventional type blending equipment heated to about200-250° C. The nylon material and the copolymer, terpolymer, terpolymerionomer, and/or copolymer ionomer preferably are dried (eitherindividually or together) before melt blending. Drying is done indesiccated air at a temperature and for a time suitable to reduce themoisture content to a point which it will not have any adverse effect onthe subsequent use of the compositions or the properties of theresulting product. If additives such as those identified above have notpreviously been added to either the nylon material, the copolymer orcopolymer ionomer during processing of those individual components,i.e., before they are admixed with each other, the additives may beadded during melt blending of those components. The uniform admixtureresulting from the melt blending procedure then may be commuted bychopping, pelletizing or grinding into granules, pellets, chips, flakesor powders suitable for subsequent use, e.g. injection molding toprovide a golf ball.

The invention has been described with reference to the preferredembodiments. Modification and alterations will occur to others uponreading and understanding the preceding detailed description. It isintended that the invention be construed as including all suchalterations and modifications insofar as they come within the scope ofthe claims and the equivalents thereof.

What is claimed is:
 1. A golf ball having a cover layer wherein saidcover layer is formed from a resin composition comprising a combinationof three components wherein said components comprise a polyamidecomponent, an ionomeric component, and an ester component, the contentof the polyamide component being at least 23 wt. % of the resincomposition, the golf ball having a coefficient of restitution of atleast 0.750.
 2. A golf ball according to claim 1, wherein the polyamidecomponent includes at least one member selected from the groupconsisting of a polyamide homopolymer and a polyamide copolymer.
 3. Agolf ball according to claim 1, wherein at least a portion of thepolyamide component and the ionomeric component are part of the samecopolymer.
 4. A golf ball according to claim 1, wherein the combinationof the polyamide component and ionomeric component is a reactionproduct.
 5. A golf ball according to claim 1, wherein the polyamidecomponent is present in a mixture with the ionomeric component.
 6. Agolf ball according to claim 1, wherein the golf ball has a DurabilityRating of at least
 2. 7. A golf ball according to claim 1, wherein thecombination has 23-85 weight % polyamide component, and 15-77 weight %ionomeric component.
 8. A golf ball according to claim 1, wherein thepolyamide in the polyamide component includes at least one memberselected from the group consisting of polyepsiloncaprolactam andpolyhexamethyleneadipamide.
 9. A golf ball according to claim 1, whereinthe ester component is an olefin ester copolymer component.
 10. A golfball according to claim 1, wherein at least a portion of each of theester component, polyamide component and ionomeric component are part ofthe same copolymer.
 11. A golf ball according to claim 9, wherein thecombination of the polyamide component, ionomer component and olefinester copolymer component comprises a reaction product.
 12. A golf ballaccording to claim 10, wherein the composition further comprises acarboxylic acid-containing copolymer which includes at least one memberselected from the group consisting of ionomeric copolymers andnon-ionomeric copolymers and which is mixed with the reaction product.13. A golf ball according to claim 1, wherein the ionomeric componentincludes an alkyl acrylate.
 14. A golf ball according to claim 1,wherein the polyamide component is a polyamide homopolymer and theionomeric component is an ionomeric copolymer with two types ofmonomers.
 15. A golf ball according to claim 1, wherein the polyamidecomponent is a polyamide homopolymer and the ionomeric component is anionomeric terpolymer.
 16. A method of making a golf ball, comprising thesteps of: obtaining a golf ball core, and forming a cover layer over thecore, the cover layer having a three component resin compositioncomprising a combination of a polyamide component, an ionomericcomponent, and an ester component, the content of the polyamidecomponent being at least 23 wt. % of the resin composition, the golfball having a coefficient of restitution of at least 0.750.
 17. A golfball according to claim 16, wherein the ester component is an olefinester copolymer component.
 18. A golf ball according to claim 17,wherein the combination of the polyamide component, ionomeric componentand olefin ester copolymer component comprises a reaction product.
 19. Agolf ball according to claim 16, wherein at least a portion of each ofthe ester component, polyamide component, and ionomeric component arepart of the same copolymer.
 20. A golf ball having a cover layer with athree component composition comprising a graft copolymer of (1) at leastone of a polyamide homopolymer and a polyamide copolymer, (2) a firstionomeric copolymer which is formed from an α-olefin and a carboxylicacid, and (3) an ester component, the cover layer having a Shore Dhardness of at least 30,the golf ball having a Durability Rating of atleast
 2. 21. A golf ball according to claim 20, wherein the cover layerfurther includes a second ionomeric copolymer which is blended with thegraft copolymer.
 22. A golf ball according to claim 20, wherein thecover layer has a Shore D hardness of 30-60.
 23. A golf ball accordingto claim 20, wherein the cover layer has a Shore D hardness of at least65.
 24. A golf ball according to claim 20, wherein the polyamidehomopolymer includes at least one member selected from the groupconsisting of polyepsiloncaprolactam and polyhexamethyleneadipamide. 25.A golf ball according to claim 20, wherein the ester component is anolefin ester copolymer component.
 26. A golf ball having a cover layerwith a three component composition comprising a nylon backbone with anionomer grafted thereto and an ester component, the golf ball having acoefficient of restitution of at least 0.750.
 27. A golf ball accordingto claim 26, wherein the cover layer has a Shore D hardness of 30-60.28. A golf ball according to claim 26, wherein the cover layer has aShore D hardness of at least
 65. 29. A golf ball according to claim 26,wherein the ester component is an olefin ester copolymer component. 30.A golf ball having a cover layer with a three component resincomposition comprising at least 10 wt. % of a graft copolymer ofpolyepsiloncaprolactam and ionomer, further wherein the covercomposition includes an ester component, the graft copolymer having ayield tensile strength of about 54 MPA (ASTM D-638), a flexural modulusof about 1585 MPA (ASTM D-790), and a drop weight impact at −40° F. ofabout 200J (ASTM D-3029).
 31. A golf ball according to claim 30,wherein, the resin composition includes an ionomeric terpolymer blendedwith the graft copolymer.
 32. A golf ball according to claim 31, whereinthe resin composition comprises at least 80 wt % of the graft copolymer.33. A golf ball according to claim 30 wherein the ester component is anolefin ester copolymer component.